Method of manufacturing tubes and pipes



Aug. 6, 1935. L. KLEIN 2,010,400

METHOD OF MANUFACTURING TUBES ANDA PIPES Filed Feb. 19, 1932 Ihren/or.-z. /f am l Patented Aug. 6, 1935 UNITED STATES PATENT OFFICE METHOD F`MANUFACTURING TUBES AND PIPES Application February 19, 1932, Serial No.594,127 In Germany May 11, 1931 e claims'. (C1. sli-62) My prior PatentNo. 1,898,779 relates to a method of producing tubes and pipes withinternally thickened ends by the pilgering process with the aid of amandrel having an offset, the main feature being that while thethickened tube ,end is being rolled out over the oiset portion of themandrel and during the time in which the rolls in rolling out thematerial over the part of the mandrel of normal thickness are stillopera.- tive at the offset part of the mandrel, the material is expandedrearwards.

The object of the present invention is to apply this method to themanufacture of tubes and pipes of a desired length which have not only1,. thickened ends, but have in general local inwardly extendingthickenings at desired points.. Such pipes are used for instance ascolumns and generally in vall cases where a pipe having a smoothcylindrical external surface must at certain places 20 have a thickenedcross-section for considerations of strength or for other reasons.

The invention relates moreover to tubes and pipes of a desired lengthwhich have local inwardly extending thickenings manufactured by thepilgering process with the aid of a mandrel having an offset portion,wherein said thickenings can be formed at desired and predeterminedpoints along the inside of the tube or pipe, and independent of thelength of the same such as to pro-l 30 duce tubes or pipes of a desiredlength with a desired number of said internal thickenings in desiredspaces. Moreover the invention comprises the finished tube or pipe of adesired length which is provided at its one end and at predeterminedpoints along its inside with local inwardly extending thickenings and atits other end with an outwardly extending thickening.

The method according to the invention is also suitable for themanufacture of tubular rods with inwardly thickened ends when the tubesare to be made not in single but in double or multiple lengths. Throughthe application of the new method for this purpose the output of therolling ,mill is considerably increased, the waste of ma.-

4l terial reduced and the percentage turned out imy proved, so that themanufacturing costs become considerably lower.

The manufacture of tubes of a desired length with local inwardlyextending thickenings at desired points is carried out according to theinvention by the tubular blank being rolled down on the thicker part ofa mandrel having an'oiiset end until a place which is to be thickenedinternally is reached, thereupon moving longitudinally and u securingthe blank in place with respect to the mandrel in such a position thatthe material for producing the thickening encloses the offset endportion of the mandrel, and then rolling down the thickened part of theblank on said oilset portion. After this rolling down cf the thickeningthe work piece may be released on the mandrel for enabling the blank tobe further rolled down.

For xing the blank with respect to the mandrel during the rolling downof the thickening a bridging piece is placed over the exposed portion ofthe part of the mandrel of normal thickness, which bears at both endsagailnst a stripping ring and an auxiliary ring respectively. After thethickening has beenl rolled the bridging piece is removed for enablingthe next part of the tube of normal cross-section to be rolled down.Through the part of the mandrel of normal thickness becoming availableagain and through the blank resting with the thickening just formedagainst the oiset on the mandrel the exact rolling of the blank over theoffset on the mandrel becomes possible, that is to say, the, materialcan yield rearwardly when rolling down the place where the thick-walledcross-section merges into the thin-walled cross-section.

In the accompanying drawing different phases of the method according tothe invention are illustrated on a constructional example.

In Fig. l, of which Fig. la represents a section along y-y, the tubularblank a is provided at its forward end in accordance with the methoddescribed lin my said prior patent with an inwardly extending thickeningand has been rolled down next to this thickening over a certain lengthto the normal tubular'cross-section. In order to produce at a desiredplace an inwardlyextending local thickening, the blank is held withrespect to the mandrel in such a position that the material required forproducing the thickening is over tion, the bridging piece d has beenremoved. For

this reason and because the blank bears with the thickening justproduced against the shoulder g of the mandrel, in rolling down thetransitional part the material can yield rearwardly,

until the rings e and f bear against one another 5 as shown in Fig. 3,whereupon the rolling down oi the tube proceeds in the normal manner,that is to say, the material is stretched out forwardly. The outwardlyextending thickening or pilger head a remaining at the rear end of thetube, as shown in Fig. 3, may thereupon be rolleddown in the mannerdescribed in my said prior patent so as to produce an inwardly thickenedtube end.

Instead of making one local inwardly extending thickening in addition tothe inwardly thickened tube ends, `it is of course possible to make anynumber ofthickenings by the new method.

What I claim is:

l. A method of manufacturing a tube or pipe having local inwardlyextending thickenings at desired points, consisting in rolling down atubular blank on the thicker part of a mandrel having an offset endsmaller than its other portions until a place which is to be thickenedinternally is reached, thereupon moving longitudinally and securing theblank in place with respect to the mandrel in such a position that thematerial for producing the thickening encloses the oiset end portion ofthe mandrel, and then rolling down. the thickened partici the blank onsaid offset end portion, as set forth.

2. A method of manufacturing tubes and pipes of a desired length with'local inwardly extending thickenings atA desired points, consisting inrolling down a tubular blank on the thicker part of a mandrel having asmaller offset portion until a place is reached which is to be thickenedinternally, thereupon moving the blank or mandrel longitudinally withrespect the one to the other andl securing the blank with respect to themandrel in such a position that the material for producing thethickening encloses the smaller offset portion of the mandrel, thenrolling down the thickened part of the blank onto said offset andreleasing the blank with respect to the mandrel for enabling the blankto be further moved longitudinally and rolled down, as and for thepurpose set forth. I

3. /A method of manufacturing tubes and pipes of a desired'length withlocal inwardly extending thickenings at desired points, consisting inrolling down on a mandrel having different diameters a tubular blank onthe thicker part of the mandrel having a smaller offset end portionuntil a place is reached which is to be thickened internally, thereuponplacing a bridging piece covering only a part of the circumference ofthe mandrel on the exposed part of the mandrel, whereby the thickeningsat desired points, consisting in rollv ing dow-n a tubular blank on thethicker part of a mandrel having a smaller offset end portion until aplace is reached which is to b e thickened lnternally, thereupon placinga bridging piece covering only a part of the circumference of themandrel on the exposed part of the mandrel, thereby securing the blankfrom longitudinal motion with respect to the mandrel in such a positionthat the material for producing the thickening encloses the oisetportion of the mandrel, then rolling down the thickened part of theblank and thereupon removing the bridging piece from the mandrel therebyreleasing the blank with respect to the mandrel for enabling the blankto be further rolled down, as and for the purpose set forth.

5. A. method of manufacturing a tube or pipe having local inwardlyextending thickenings at de'sired points consisting in rolling down atubular blank which has been constricted near its front end on thesmaller offset end portion of a mandrel so as to produce an inner endthickening of the blank, thereupon rolling out the blank on the thickerpart of the mandrel until a place is reached which. is to be thickenedinternally, thereupon moving the blank longitudinally with respect tothe mandrel and securing the blank with respect to the mandrelA in sucha position that the material for producing the thickening encloses thesmaller oiset portion of the mandrel, then rolling down the thickenedpart of the blank onto said offset, releasing'the blank with respect tothe mandrel for enabling the blank to be further moved longitudinallyand rolled down in its normal thickness and rolling an inner thickeningat the rear end of the blank.

6. A tube or pipe of a desired length being provided at its one end andat predetermined LUDWG KLEIN.

